In conventional oil well drilling operations, a drill bit is attached to the lower end of a drill pipe which is run down into the well by a rotating kelly. The kelly has a hexagonally or polygonally shaped cross-section to facilitate rotation of it by a rotary table. To prevent the loss of drilling mud or well fluids, a rotating blowout preventer mounted between the rotary table and the wellhead engages a tight fluid seal about the kelly or drill pipe. The downward motion of the kelly or drill tool combined with the rotation of the kelly or tool subjects this fluid seal to vertical as well as radial loads. The fluid pressures in the well subject this seal to additional vertical loading.
Conventional stationary blowout preventers heretofore have employed a hydraulically operated wedging type piston to radially compress an annular packing about a production pipe to form a tight fluid seal capable of resisting the internal well pressure forces.
Heretofore, rotating blowout preventers have not been able to take advantage of a hydraulic wedging force to form a radially compressible tight fluid seal about a rotating drill pipe or irregularly shaped kelly during drilling operations. Prior blowout preventers such as the Jones rotating blowout preventer U.S. Pat. No. 3,492,007 have used only horizontal forces to radially compress an annular packing about a rotating drill pipe or kelly. The Shaffer device, U.S. Pat. No. 3,587,734 adds a rotatably mounted stripper seal to a conventional stationary blowout preventer to provide the necesary fluid seal rather than hydraulically wedging an annular packing about a rotating drill pipe or kelly.
The advantages of an oil well pipe seal engaged by a hydraulic wedging force are well known in the art. Furthermore, such a sealing method has been proven effective in the environment of stationary blowout preventers.
The primary object of this invention is to disclose and provide an effective, economical and simply constructed high pressure seal around a rotating drill pipe or kelly whose construction is also compatible with proven stationary blowout preventer components.
It is another object of this invention to utilize a conventional, radially compressible seal of known sealing capacity in a rotating blowout preventer, wherein the advantages of a radially compressible seal engaged by a hydraulic wedging force are obtained.
It is another object of this invention to construct a rotating blowout preventer from stationary blowout preventer components which are readily available and less expensive than custom made components.
It is a further object of this invention to disclose and provide an improved bearing support for a rotating blowout preventer.